Chairman of the Supreme Election Board (YSK) Sadi Güven on Monday defended the decision to allow votes that did not bear official seals to be counted alongside checked ballots.

In a news conference in Ankara, Güven said, "The voting papers and envelopes that were claimed to be void and disputed since the evening are YSK-made, real, legitimate, non-fake ballots."

During Sunday night's count, the YSK suddenly announced that unverified votes, which had not been authenticated as genuine by election officials, would be allowed.This led to a protest by the main opposition Republican People's Party (CHP), which said it would challenge the result, complaining about other violations being made during the vote.

CHP Chairman Kemal Kılıçdaroğlu said: "We respect the nation's will but the decision on unsealed ballots overshadows it." However, Güven said: "We decided with the political parties to count the non-sealed ballots." The chairman added: "It is not right to attribute a meaning to this decision."

The poll resulted in a 51.41 percent victory for the "yes" campaign, heralding the adoption of an 18-article bill that includes provisions for an executive presidency.

Earlier, Güven said a "unanimous decision" had been made before transferring the unverified votes to the system. "Before counting, ballots, the envelopes and voters' numbers are cross checked," he said speaking at the YSK office in Ankara. He added that unsealed voting envelopes have been included in past elections.

The final results will be released within 12 days, Güven said.